Health monitoring:
- gitserver: /health endpoint on port 8021 (DB + Redis ping)
- git-hook: hyper health server on port 8083 with /health
- email-worker: hyper health server on port 8084 with /health
- K8s probes updated to httpGet for all three services
Metrics (via /metrics endpoint):
- git-hook: hook_tasks_total/success/failed/locked/retried/exhausted,
hook_sync_branches/tags_changed_total
- email: email_queued/consumed/sent/failed_total,
email_validation_skipped/build_errors/send_attempts_total
- apps/app: remove mod logging, replace init_tracing_subscriber() call,
remove slog macros from main.rs, remove logging.rs
- apps/gitserver: remove slog usage from main.rs
- apps/git-hook: remove slog from main.rs
- apps/email: remove slog from main.rs
